PosterPDF Available

Does iPhone Night Shift Improve Sleep Latency and Sleep Quality In Emerging Adults?


Poster presented at Pediatric Sleep Medicine Conference in 2019.
Campsen, N. A., & Buboltz, W. C. (2017). Lifestyle Factors’ Impact on Sleep of College
Students. Austin J Sleep Disord, 4(1), 1028.
Chang, A. M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of light-
emitting eReaders negatively affects sleep, circadian timing, and next-morning
alertness. Proceedings of the National Academy of Sciences, 112(4), 1232-1237.
Chellappa, S. L., Steiner, R., Oelhafen, P., Lang, D., Götz, T., Krebs, J., & Cajochen, C.
(2013). Acute exposure to evening blueenriched light impacts on human sleep. Journal of
sleep research, 22(5), 573-580.
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(2014). Effects of exposure to intermittent versus continuous red light on human circadian
rhythms, melatonin suppression, and pupillary constriction. PLoS One, 9(5), e96532.
Pew Research Center Mobile Fact Sheet (2017, January). Retrieved October 10, 2017
Results & Discussion
Across groups, participants slept an average of 6.73
hours (SD = 0.56). Only one participant slept an
average of 8 hours or longer.
Average sleep onset latency was 12.31 minutes
(SD = 8.15)
Average sleep efficiency was 83.65% (SD = 6.29)
Average minutes of wake after sleep onset (WASO)
was 67.67 (SD = 30.32)
We ran a series of general linear models to compare
phone usage (3 groups; Night Shift, regular, and no
phone) on sleep onset latency, total sleep time, sleep
efficiency, and WASO.
There was no statistically significant effect of
condition on sleep onset latency, total sleep time,
sleep efficiency, and WASO.
This may be partially attributable to our participants
being chronically sleep restricted
In chronically sleep
restricted emerging
adults, phone use
before bed (regardless
of use of iPhone Night
Shift) does not impact
167 emerging adults (ages 18-25; Mean age =
20.85, SD = 2.13, 65.8% female) who owned and
used an iPhone daily participated in this study
Participants were excluded based on diagnosed
sleep disorders and irregular sleep schedules
Participants were randomized into one of the
following conditions for seven nights:
No phone for one hour prior to bed (N = 60)
Regular phone use for one hour prior to bed
(N = 51)
Phone use with Night Shift feature turned on for
one hour prior to bed (N = 56)
Participants’ sleep was tracked with a wrist-worn
Actigraph GT3x+ and phone use was tracked with
the Moment application
Human circadian rhythms are highly dependent on
light/dark cycles (Mein et al., 2014)
Light exposure from electronic devices can delay
sleep onset and circadian rhythm (Chang et al.,
Blue wave light is most likely to create alertness
(Chellappa, 2015)
Apple’s iPhone has created the Night Shift
feature to reduce blue wave light exposure
No studies have examined the effects of Night
Shift usage on sleep outcomes
Ninety-five percent of college students own a
smartphone (Pew, 2017), and the majority of
college students are not obtaining adequate sleep
(Campsen & Buboldz, 2017)
Aim: Examine potential differences in sleep
outcomes using iPhone Night Shift compared to
two control conditions (light exposure with no Night
Shift, no light exposure)
Hypothesis: Participants using Night Shift before
bed will demonstrate superior sleep outcomes
compared to phone use without Night Shift, but
poorer sleep outcomes compared to no phone use
Does iPhone Night Shift Improve Sleep Latency and Sleep Quality
In Emerging Adults?
Kara McRae Duraccio, Ph.D., Kelsey K. Zaugg, & Chad D. Jensen, Ph.D.
Sleep Outcome
Mean (SD)
Sig between
No Phone
11.71 (7.81)
= .73
Regular Phone
12.37 (6.94)
12.92 (9.51)
No Phone
83.78 (6.58)
= .88
Regular Phone
83.87 (6.77)
Total Sleep Time
No Phone
6.68 (0.59)
= .50
Regular Phone
6.74 (0.59)
6.80 (0.51)
No Phone
67.57 (32.62)
= .79
Regular Phone
65.61 (31.25)
69.67 (30.32)
ResearchGate has not been able to resolve any citations for this publication.
Full-text available
Transitioning to college is often met with distinct lifestyle factors that differ from those individuals who do not make such a transition. Such factors include alcohol consumption, caffeine consumption, psychostimulant use, dietary habits, class schedules, and physical activity. These lifestyle factors may impact the sleep length and quality of college students, which leads to other outcomes. Research has explored the relationship between some of these factors and sleep among college students with mixed results. The purpose of this study was to examine the relationship between several lifestyle factors of college students and their impact on the length and quality of sleep. Results indicated that food choice and physical activity are significantly related to sleep quality. Additionally, the amount of caffeine consumed was determined to be related to sleep quality. For sleep length, both amount of caffeine consumed and average hours worked per week were related to sleep length. Although some factors were determined not to predict sleep quality or sleep length, results indicated that there are several specific lifestyle factors associated with being a college student that impact sleep length and sleep quality. Thus, colleges and universities should evaluate the amount and quality of sleep of their students.
Full-text available
Exposure to light is a major determinant of sleep timing and hormonal rhythms. The role of retinal cones in regulating circadian physiology remains unclear, however, as most studies have used light exposures that also activate the photopigment melanopsin. Here, we tested the hypothesis that exposure to alternating red light and darkness can enhance circadian resetting responses in humans by repeatedly activating cone photoreceptors. In a between-subjects study, healthy volunteers (n = 24, 21-28 yr) lived individually in a laboratory for 6 consecutive days. Circadian rhythms of melatonin, cortisol, body temperature, and heart rate were assessed before and after exposure to 6 h of continuous red light (631 nm, 13 log photons cm-2 s-1), intermittent red light (1 min on/off), or bright white light (2,500 lux) near the onset of nocturnal melatonin secretion (n = 8 in each group). Melatonin suppression and pupillary constriction were also assessed during light exposure. We found that circadian resetting responses were similar for exposure to continuous versus intermittent red light (P = 0.69), with an average phase delay shift of almost an hour. Surprisingly, 2 subjects who were exposed to red light exhibited circadian responses similar in magnitude to those who were exposed to bright white light. Red light also elicited prolonged pupillary constriction, but did not suppress melatonin levels. These findings suggest that, for red light stimuli outside the range of sensitivity for melanopsin, cone photoreceptors can mediate circadian phase resetting of physiologic rhythms in some individuals. Our results also show that sensitivity thresholds differ across non-visual light responses, suggesting that cones may contribute differentially to circadian resetting, melatonin suppression, and the pupillary light reflex during exposure to continuous light.
In the past 50 y, there has been a decline in average sleep duration and quality, with adverse consequences on general health. A representative survey of 1,508 American adults recently revealed that 90% of Americans used some type of electronics at least a few nights per week within 1 h before bedtime. Mounting evidence from countries around the world shows the negative impact of such technology use on sleep. This negative impact on sleep may be due to the short-wavelength-enriched light emitted by these electronic devices, given that artificial-light exposure has been shown experimentally to produce alerting effects, suppress melatonin, and phase-shift the biological clock. A few reports have shown that these devices suppress melatonin levels, but little is known about the effects on circadian phase or the following sleep episode, exposing a substantial gap in our knowledge of how this increasingly popular technology affects sleep. Here we compare the biological effects of reading an electronic book on a light-emitting device (LE-eBook) with reading a printed book in the hours before bedtime. Participants reading an LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock, and reduced next-morning alertness than when reading a printed book. These results demonstrate that evening exposure to an LE-eBook phase-delays the circadian clock, acutely suppresses melatonin, and has important implications for understanding the impact of such technologies on sleep, performance, health, and safety.
Light in the short wavelength range (blue light: 446-483 nm) elicits direct effects on human melatonin secretion, alertness and cognitive performance via non-image-forming photoreceptors. However, the impact of blue-enriched polychromatic light on human sleep architecture and sleep electroencephalographic activity remains fairly unknown. In this study we investigated sleep structure and sleep electroencephalographic characteristics of 30 healthy young participants (16 men, 14 women; age range 20-31 years) following 2 h of evening light exposure to polychromatic light at 6500 K, 2500 K and 3000 K. Sleep structure across the first three non-rapid eye movement non-rapid eye movement - rapid eye movement sleep cycles did not differ significantly with respect to the light conditions. All-night non-rapid eye movement sleep electroencephalographic power density indicated that exposure to light at 6500 K resulted in a tendency for less frontal non-rapid eye movement electroencephalographic power density, compared to light at 2500 K and 3000 K. The dynamics of non-rapid eye movement electroencephalographic slow wave activity (2.0-4.0 Hz), a functional index of homeostatic sleep pressure, were such that slow wave activity was reduced significantly during the first sleep cycle after light at 6500 K compared to light at 2500 K and 3000 K, particularly in the frontal derivation. Our data suggest that exposure to blue-enriched polychromatic light at relatively low room light levels impacts upon homeostatic sleep regulation, as indexed by reduction in frontal slow wave activity during the first non-rapid eye movement episode.